This CL exposes zoom modes to the <webview> API.

The new api is proposed here: https://docs.google.com/a/google.com/document/d/1hIexgq7HvYbqTp19HklW6DcKW-5sgocmnCqUHDKsYo0/edit?usp=sharing

BUG=472674

Review URL: https://codereview.chromium.org/1047793003

Cr-Commit-Position: refs/heads/master@{#323300}

15 files changed, 427 insertions, 37 deletions

diff --git a/chrome/browser/apps/guest_view/web_view_browsertest.cc b/chrome/browser/apps/guest_view/web_view_browsertest.cc
index 14b2f9f..9b82907 100644
--- a/chrome/browser/apps/guest_view/web_view_browsertest.cc
+++ b/chrome/browser/apps/guest_view/web_view_browsertest.cc
@@ -2628,6 +2628,18 @@ IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestResizeEvents) {
   TestHelper("testResizeEvents", "web_view/shim", NO_TEST_SERVER);
 }
 
+IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestPerOriginZoomMode) {
+  TestHelper("testPerOriginZoomMode", "web_view/shim", NO_TEST_SERVER);
+}
+
+IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestPerViewZoomMode) {
+  TestHelper("testPerViewZoomMode", "web_view/shim", NO_TEST_SERVER);
+}
+
+IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestDisabledZoomMode) {
+  TestHelper("testDisabledZoomMode", "web_view/shim", NO_TEST_SERVER);
+}
+
 // This test verify that the set of rules registries of a webview will be
 // removed from RulesRegistryService after the webview is gone.
 // http://crbug.com/438327
diff --git a/chrome/common/extensions/api/tabs.json b/chrome/common/extensions/api/tabs.json
index 4fe70c7..1fa5887 100644
--- a/chrome/common/extensions/api/tabs.json
+++ b/chrome/common/extensions/api/tabs.json
@@ -50,7 +50,7 @@
               },
               {
                 "name": "disabled",
-                "description": "Disables all zooming in the tab. The tab will revert to default (100%) zoom, and all attempted zoom changes will be ignored."
+                "description": "Disables all zooming in the tab. The tab will revert to the default zoom level, and all attempted zoom changes will be ignored."
               }
             ]
           },
diff --git a/chrome/common/extensions/api/webview_tag.json b/chrome/common/extensions/api/webview_tag.json
index 53f69c6..7f9fa03 100644
--- a/chrome/common/extensions/api/webview_tag.json
+++ b/chrome/common/extensions/api/webview_tag.json
@@ -312,6 +312,25 @@
         "type": "object",
         "description": "Interface which provides access to webRequest events on the guest page. See the <a href=\"http://developer.chrome.com/extensions/webRequest\">chrome.webRequest</a> extensions API for details on webRequest life cycle and related concepts.<p>To illustrate how usage differs from the extensions webRequest API, consider the following example code which blocks any guest requests for URLs which match <code>*://www.evil.com/*</code>:</p><pre>webview.request.onBeforeRequest.addListener(\r  function(details) { return {cancel: true}; },\r  {urls: [\"*://www.evil.com/*\"]},\r  [\"blocking\"]);</pre><p>Additionally, this interface supports declarative webRequest rules through <code>onRequest</code> and <code>onMessage</code> events. See <a href=\"http://developer.chrome.com/extensions/declarativeWebRequest.html\">declarativeWebRequest</a> for API details.</p>Note that conditions and actions for declarative webview webRequests should be instantiated from their <code>chrome.webViewRequest.*</code> counterparts. The following example code declaratively blocks all requests to <code>\"example.com\"</code> on the webview <code>myWebview</code>:</p><pre>var rule = {\r  conditions: [\r    new chrome.webViewRequest.RequestMatcher({ url: { hostSuffix: 'example.com' } })\r  ],\r  actions: [ new chrome.webViewRequest.CancelRequest() ]\r};\rmyWebview.request.onRequest.addRules([rule]);</pre>",
         "properties": {}
+      },
+      {
+        "id": "ZoomMode",
+        "type": "string",
+        "description": "Defines the how zooming is handled in the webview.",
+        "enum": [
+          {
+            "name": "per-origin",
+            "description": "Zoom changes will persist in the zoomed page's origin, i.e. all other webviews in the same partition that are navigated to that same origin will be zoomed as well. Moreover, <code>per-origin</code> zoom changes are saved with the origin, meaning that when navigating to other pages in the same origin, they will all be zoomed to the same zoom factor."
+          },
+          {
+            "name": "per-view",
+            "description": "Zoom changes only take effect in this webview, and zoom changes in other webviews will not affect the zooming of this webview. Also, <code>per-view</code> zoom changes are reset on navigation; navigating a webview will always load pages with their per-origin zoom factors (within the scope of the partition)."
+          },
+          {
+            "name": "disabled",
+            "description": "Disables all zooming in the webview. The content will revert to the default zoom level, and all attempted zoom changes will be ignored."
+          }
+        ]
       }
     ],
     "functions": [
@@ -455,6 +474,25 @@
         ]
       },
       {
+        "name": "getZoomMode",
+        "type": "function",
+        "description": "Gets the current zoom mode.",
+        "parameters": [
+          {
+            "type": "function",
+            "name": "callback",
+            "description": "Called with the webview's current zoom mode.",
+            "parameters": [
+              {
+                "$ref": "ZoomMode",
+                "name": "ZoomMode",
+                "description": "The webview's current zoom mode."
+              }
+            ]
+          }
+        ]
+      },
+      {
         "name": "go",
         "type": "function",
         "description": "Navigates to a history entry using a history index relative to the current navigation. If the requested navigation is impossible, this method has no effect.",
@@ -545,6 +583,25 @@
         ]
       },
       {
+        "name": "setZoomMode",
+        "type": "function",
+        "description": "Sets the zoom mode of the webview.",
+        "parameters": [
+          {
+            "$ref": "ZoomMode",
+            "name": "ZoomMode",
+            "description": "Defines how zooming is handled in the webview."
+          },
+          {
+            "type": "function",
+            "name": "callback",
+            "description": "Called after the zoom mode has been changed.",
+            "optional": true,
+            "parameters": []
+          }
+        ]
+      },
+      {
         "name": "stop",
         "type": "function",
         "description": "Stops loading the current &lt;webview> navigation if in progress.",
diff --git a/chrome/test/data/extensions/platform_apps/web_view/shim/main.js b/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
index 31d1c37..0b116a8 100644
--- a/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
+++ b/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
@@ -2043,7 +2043,7 @@ function testLoadDataAPI() {
             embedder.test.succeed();
           });
         });
-  }
+  };
 
   var loadstopListener1 = function(e) {
     webview.removeEventListener('loadstop', loadstopListener1);
@@ -2055,7 +2055,7 @@ function testLoadDataAPI() {
         "BhIHRlc3QuPGJyPgogIDxpbWcgc3JjPSJ0ZXN0LmJtcCI+PGJyPgo8L2h0bWw+Cg==",
                                 embedder.testImageBaseURL,
                                 embedder.virtualURL);
-  }
+  };
 
   webview.addEventListener('loadstop', loadstopListener1);
   document.body.appendChild(webview);
@@ -2104,6 +2104,103 @@ function testResizeEvents() {
   document.body.appendChild(webview);
 };
 
+function testPerOriginZoomMode() {
+  var webview1 = new WebView();
+  var webview2 = new WebView();
+  webview1.src = 'about:blank';
+  webview2.src = 'about:blank';
+
+  webview1.addEventListener('loadstop', function(e) {
+    document.body.appendChild(webview2);
+  });
+  webview2.addEventListener('loadstop', function(e) {
+    webview1.getZoomMode(function(zoomMode) {
+      // Check that |webview1| is in 'per-origin' mode and zoom it. Check that
+      // both webviews zoomed.
+      embedder.test.assertEq(zoomMode, 'per-origin');
+      webview1.setZoom(3.14, function() {
+        webview1.getZoom(function(zoom) {
+          embedder.test.assertEq(zoom, 3.14);
+          webview2.getZoom(function(zoom) {
+            embedder.test.assertEq(zoom, 3.14);
+            embedder.test.succeed();
+          });
+        });
+      });
+    });
+  });
+
+  document.body.appendChild(webview1);
+}
+
+function testPerViewZoomMode() {
+  var webview1 = new WebView();
+  var webview2 = new WebView();
+  webview1.src = 'about:blank';
+  webview2.src = 'about:blank';
+
+  webview1.addEventListener('loadstop', function(e) {
+    document.body.appendChild(webview2);
+  });
+  webview2.addEventListener('loadstop', function(e) {
+    // Set |webview2| to 'per-view' mode and zoom it. Make sure that the
+    // zoom did not affect |webview1|.
+    webview2.setZoomMode('per-view', function() {
+      webview2.getZoomMode(function(zoomMode) {
+        embedder.test.assertEq(zoomMode, 'per-view');
+        webview2.setZoom(0.45, function() {
+          webview1.getZoom(function(zoom) {
+            embedder.test.assertFalse(zoom == 0.45);
+            webview2.getZoom(function(zoom) {
+              embedder.test.assertEq(zoom, 0.45);
+              embedder.test.succeed();
+            });
+          });
+        });
+      });
+    });
+  });
+
+  document.body.appendChild(webview1);
+}
+
+function testDisabledZoomMode() {
+  var webview = new WebView();
+  webview.src = 'about:blank';
+
+  var zoomchanged = false;
+  var zoomchangeListener = function(e) {
+    // TODO (paulmeyer): This is currently broken because ZoomObservers do not
+    // get the correct new zoom level when changing the zoom mode to
+    // 'disabled'. Will add back in after http://crbug.com/472621 is fixed.
+    //embedder.test.assertEq(e.newZoomFactor, 1);
+    zoomchanged = true;
+  };
+
+  webview.addEventListener('loadstop', function(e) {
+    // Set |webview| to 'disabled' mode and check that
+    // zooming is actually disabled. Also check that the
+    // "zoomchange" event pick up changes from changing the
+    // zoom mode.
+    webview.addEventListener('zoomchange', zoomchangeListener);
+    webview.setZoomMode('disabled', function() {
+      webview.getZoomMode(function(zoomMode) {
+        embedder.test.assertEq(zoomMode, 'disabled');
+        webview.removeEventListener('zoomchange', zoomchangeListener);
+        webview.setZoom(1.39, function() {
+          webview.getZoom(function(zoom) {
+            embedder.test.assertEq(zoom, 1);
+            embedder.test.assertTrue(zoomchanged);
+            embedder.test.succeed();
+          });
+        });
+      });
+    });
+  });
+
+  document.body.appendChild(webview);
+}
+
 embedder.test.testList = {
   'testAllowTransparencyAttribute': testAllowTransparencyAttribute,
   'testAutosizeHeight': testAutosizeHeight,
@@ -2182,7 +2279,10 @@ embedder.test.testList = {
   'testFindAPI': testFindAPI,
   'testFindAPI_findupdate': testFindAPI,
   'testLoadDataAPI': testLoadDataAPI,
-  'testResizeEvents': testResizeEvents
+  'testResizeEvents': testResizeEvents,
+  'testPerOriginZoomMode': testPerOriginZoomMode,
+  'testPerViewZoomMode': testPerViewZoomMode,
+  'testDisabledZoomMode': testDisabledZoomMode,
 };
 
 onload = function() {
diff --git a/components/ui/zoom/zoom_controller.h b/components/ui/zoom/zoom_controller.h
index ff78b86..0ea9f6b 100644
--- a/components/ui/zoom/zoom_controller.h
+++ b/components/ui/zoom/zoom_controller.h
@@ -57,8 +57,8 @@ class ZoomController : public content::WebContentsObserver,
     // These zoom changes can be handled manually by listening for the
     // |onZoomChange| event. Zooming in this mode is also on a per-tab basis.
     ZOOM_MODE_MANUAL,
-    // Disables all zooming in this tab. The tab will revert to default (100%)
-    // zoom, and all attempted zoom changes will be ignored.
+    // Disables all zooming in this tab. The tab will revert to the default
+    // zoom level, and all attempted zoom changes will be ignored.
     ZOOM_MODE_DISABLED,
   };
 
diff --git a/extensions/browser/api/guest_view/web_view/web_view_internal_api.cc b/extensions/browser/api/guest_view/web_view/web_view_internal_api.cc
index b40c012..cb68550 100644
--- a/extensions/browser/api/guest_view/web_view/web_view_internal_api.cc
+++ b/extensions/browser/api/guest_view/web_view/web_view_internal_api.cc
@@ -23,6 +23,7 @@
 using content::WebContents;
 using extensions::core_api::web_view_internal::SetPermission::Params;
 using extensions::core_api::extension_types::InjectDetails;
+using ui_zoom::ZoomController;
 namespace web_view_internal = extensions::core_api::web_view_internal;
 
 namespace {
@@ -332,12 +333,75 @@ bool WebViewInternalGetZoomFunction::RunAsyncSafe(WebViewGuest* guest) {
       web_view_internal::GetZoom::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  double zoom_factor = guest->zoom();
+  double zoom_factor = guest->GetZoom();
   SetResult(new base::FundamentalValue(zoom_factor));
   SendResponse(true);
   return true;
 }
 
+WebViewInternalSetZoomModeFunction::WebViewInternalSetZoomModeFunction() {
+}
+
+WebViewInternalSetZoomModeFunction::~WebViewInternalSetZoomModeFunction() {
+}
+
+bool WebViewInternalSetZoomModeFunction::RunAsyncSafe(WebViewGuest* guest) {
+  scoped_ptr<web_view_internal::SetZoomMode::Params> params(
+      web_view_internal::SetZoomMode::Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params.get());
+
+  ZoomController::ZoomMode zoom_mode = ZoomController::ZOOM_MODE_DEFAULT;
+  switch (params->zoom_mode) {
+    case web_view_internal::ZOOM_MODE_PER_ORIGIN:
+      zoom_mode = ZoomController::ZOOM_MODE_DEFAULT;
+      break;
+    case web_view_internal::ZOOM_MODE_PER_VIEW:
+      zoom_mode = ZoomController::ZOOM_MODE_ISOLATED;
+      break;
+    case web_view_internal::ZOOM_MODE_DISABLED:
+      zoom_mode = ZoomController::ZOOM_MODE_DISABLED;
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  guest->SetZoomMode(zoom_mode);
+
+  SendResponse(true);
+  return true;
+}
+
+WebViewInternalGetZoomModeFunction::WebViewInternalGetZoomModeFunction() {
+}
+
+WebViewInternalGetZoomModeFunction::~WebViewInternalGetZoomModeFunction() {
+}
+
+bool WebViewInternalGetZoomModeFunction::RunAsyncSafe(WebViewGuest* guest) {
+  scoped_ptr<web_view_internal::GetZoomMode::Params> params(
+      web_view_internal::GetZoomMode::Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params.get());
+
+  web_view_internal::ZoomMode zoom_mode = web_view_internal::ZOOM_MODE_NONE;
+  switch (guest->GetZoomMode()) {
+    case ZoomController::ZOOM_MODE_DEFAULT:
+      zoom_mode = web_view_internal::ZOOM_MODE_PER_ORIGIN;
+      break;
+    case ZoomController::ZOOM_MODE_ISOLATED:
+      zoom_mode = web_view_internal::ZOOM_MODE_PER_VIEW;
+      break;
+    case ZoomController::ZOOM_MODE_DISABLED:
+      zoom_mode = web_view_internal::ZOOM_MODE_DISABLED;
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  SetResult(new base::StringValue(web_view_internal::ToString(zoom_mode)));
+  SendResponse(true);
+  return true;
+}
+
 WebViewInternalFindFunction::WebViewInternalFindFunction() {
 }
 
diff --git a/extensions/browser/api/guest_view/web_view/web_view_internal_api.h b/extensions/browser/api/guest_view/web_view/web_view_internal_api.h
index cd23be2..650d530 100644
--- a/extensions/browser/api/guest_view/web_view/web_view_internal_api.h
+++ b/extensions/browser/api/guest_view/web_view/web_view_internal_api.h
@@ -211,6 +211,40 @@ class WebViewInternalGetZoomFunction : public WebViewInternalExtensionFunction {
   DISALLOW_COPY_AND_ASSIGN(WebViewInternalGetZoomFunction);
 };
 
+class WebViewInternalSetZoomModeFunction
+    : public WebViewInternalExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("webViewInternal.setZoomMode",
+                             WEBVIEWINTERNAL_SETZOOMMODE);
+
+  WebViewInternalSetZoomModeFunction();
+
+ protected:
+  ~WebViewInternalSetZoomModeFunction() override;
+
+ private:
+  bool RunAsyncSafe(WebViewGuest* guest) override;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewInternalSetZoomModeFunction);
+};
+
+class WebViewInternalGetZoomModeFunction
+    : public WebViewInternalExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("webViewInternal.getZoomMode",
+                             WEBVIEWINTERNAL_GETZOOMMODE);
+
+  WebViewInternalGetZoomModeFunction();
+
+ protected:
+  ~WebViewInternalGetZoomModeFunction() override;
+
+ private:
+  bool RunAsyncSafe(WebViewGuest* guest) override;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewInternalGetZoomModeFunction);
+};
+
 class WebViewInternalFindFunction : public WebViewInternalExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("webViewInternal.find", WEBVIEWINTERNAL_FIND);
diff --git a/extensions/browser/extension_function_histogram_value.h b/extensions/browser/extension_function_histogram_value.h
index 5dda98d..5c0460b 100644
--- a/extensions/browser/extension_function_histogram_value.h
+++ b/extensions/browser/extension_function_histogram_value.h
@@ -1051,6 +1051,8 @@ enum HistogramValue {
   SETTINGSPRIVATE_GETPREF,
   NETWORKINGPRIVATE_FORGETNETWORK,
   EASYUNLOCKPRIVATE_HIDEERRORBUBBLE,
+  WEBVIEWINTERNAL_SETZOOMMODE,
+  WEBVIEWINTERNAL_GETZOOMMODE,
   // Last entry: Add new entries above and ensure to update
   // tools/metrics/histograms/histograms.xml.
   ENUM_BOUNDARY
diff --git a/extensions/browser/guest_view/guest_view_base.cc b/extensions/browser/guest_view/guest_view_base.cc
index 9a00f07..899037d 100644
--- a/extensions/browser/guest_view/guest_view_base.cc
+++ b/extensions/browser/guest_view/guest_view_base.cc
@@ -265,6 +265,11 @@ void GuestViewBase::InitWithWebContents(
   if (CanRunInDetachedState())
     SetUpSizing(create_params);
 
+  // Observe guest zoom changes.
+  auto zoom_controller =
+      ui_zoom::ZoomController::FromWebContents(web_contents());
+  zoom_controller->AddObserver(this);
+
   // Give the derived class an opportunity to perform additional initialization.
   DidInitialize(create_params);
 }
@@ -701,15 +706,26 @@ GuestViewBase::~GuestViewBase() {
 
 void GuestViewBase::OnZoomChanged(
     const ui_zoom::ZoomController::ZoomChangedEventData& data) {
-  auto guest_zoom_controller =
-      ui_zoom::ZoomController::FromWebContents(web_contents());
-  if (content::ZoomValuesEqual(data.new_zoom_level,
-                               guest_zoom_controller->GetZoomLevel())) {
+  if (data.web_contents == embedder_web_contents()) {
+    // The embedder's zoom level has changed.
+    auto guest_zoom_controller =
+        ui_zoom::ZoomController::FromWebContents(web_contents());
+    if (content::ZoomValuesEqual(data.new_zoom_level,
+                                 guest_zoom_controller->GetZoomLevel())) {
+      return;
+    }
+    // When the embedder's zoom level doesn't match the guest's, then update the
+    // guest's zoom level to match.
+    guest_zoom_controller->SetZoomLevel(data.new_zoom_level);
+
+    EmbedderZoomChanged(data.old_zoom_level, data.new_zoom_level);
     return;
   }
-  // When the embedder's zoom level doesn't match the guest's, then update the
-  // guest's zoom level to match.
-  guest_zoom_controller->SetZoomLevel(data.new_zoom_level);
+
+  if (data.web_contents == web_contents()) {
+    // The guest's zoom level has changed.
+    GuestZoomChanged(data.old_zoom_level, data.new_zoom_level);
+  }
 }
 
 void GuestViewBase::DispatchEventToGuestProxy(Event* event) {
diff --git a/extensions/browser/guest_view/guest_view_base.h b/extensions/browser/guest_view/guest_view_base.h
index a7ea60a..ba9e721 100644
--- a/extensions/browser/guest_view/guest_view_base.h
+++ b/extensions/browser/guest_view/guest_view_base.h
@@ -112,6 +112,10 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
   // web contents.
   virtual void EmbedderWillBeDestroyed() {}
 
+  // This method is called when the embedder's zoom changes.
+  virtual void EmbedderZoomChanged(double old_zoom_level,
+                                   double new_zoom_level) {}
+
   // This method is called when the guest WebContents has been destroyed. This
   // object will be destroyed after this call returns.
   //
@@ -125,6 +129,9 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
   // work.
   virtual void GuestReady() {}
 
+  // This method is called when the guest's zoom changes.
+  virtual void GuestZoomChanged(double old_zoom_level, double new_zoom_level) {}
+
   // This method is called when embedder WebContents's fullscreen is toggled.
   //
   // If the guest asked the embedder to enter fullscreen, the guest uses this
@@ -296,7 +303,7 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
 
   // ui_zoom::ZoomObserver implementation.
   void OnZoomChanged(
-      const ui_zoom::ZoomController::ZoomChangedEventData& data) override;
+      const ui_zoom::ZoomController::ZoomChangedEventData& data) final;
 
   // Dispatches an event to the guest proxy.
   void DispatchEventToGuestProxy(Event* event);
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index 9ed24ff..34c4a15 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -55,6 +55,7 @@ using content::RenderFrameHost;
 using content::ResourceType;
 using content::StoragePartition;
 using content::WebContents;
+using ui_zoom::ZoomController;
 
 namespace extensions {
 
@@ -169,6 +170,14 @@ void RemoveWebViewEventListenersOnIOThread(
       view_instance_id);
 }
 
+double ConvertZoomLevelToZoomFactor(double zoom_level) {
+  double zoom_factor = content::ZoomLevelToZoomFactor(zoom_level);
+  // Because the conversion from zoom level to zoom factor isn't perfect, the
+  // resulting zoom factor is rounded to the nearest 6th decimal place.
+  zoom_factor = round(zoom_factor * 1000000) / 1000000;
+  return zoom_factor;
+}
+
 }  // namespace
 
 // static
@@ -443,6 +452,18 @@ bool WebViewGuest::IsDragAndDropEnabled() const {
   return true;
 }
 
+void WebViewGuest::GuestZoomChanged(double old_zoom_level,
+                                    double new_zoom_level) {
+  // Dispatch the zoomchange event.
+  double old_zoom_factor = ConvertZoomLevelToZoomFactor(old_zoom_level);
+  double new_zoom_factor = ConvertZoomLevelToZoomFactor(new_zoom_level);
+  scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
+  args->SetDouble(webview::kOldZoomFactor, old_zoom_factor);
+  args->SetDouble(webview::kNewZoomFactor, new_zoom_factor);
+  DispatchEventToView(
+      new GuestViewBase::Event(webview::kEventZoomChange, args.Pass()));
+}
+
 void WebViewGuest::WillDestroy() {
   if (!attached() && GetOpener())
     GetOpener()->pending_new_windows_.erase(this);
@@ -483,6 +504,16 @@ void WebViewGuest::FindReply(WebContents* source,
                          final_update);
 }
 
+double WebViewGuest::GetZoom() const {
+  double zoom_level =
+      ZoomController::FromWebContents(web_contents())->GetZoomLevel();
+  return ConvertZoomLevelToZoomFactor(zoom_level);
+}
+
+ZoomController::ZoomMode WebViewGuest::GetZoomMode() {
+  return ZoomController::FromWebContents(web_contents())->zoom_mode();
+}
+
 bool WebViewGuest::HandleContextMenu(
     const content::ContextMenuParams& params) {
   if (!web_view_guest_delegate_)
@@ -692,7 +723,6 @@ WebViewGuest::WebViewGuest(content::WebContents* owner_web_contents)
       is_overriding_user_agent_(false),
       guest_opaque_(true),
       javascript_dialog_helper_(this),
-      current_zoom_factor_(1.0),
       allow_scaling_(false),
       is_guest_fullscreen_(false),
       is_embedder_fullscreen_(false),
@@ -731,13 +761,6 @@ void WebViewGuest::DidCommitProvisionalLoadForFrame(
 
   find_helper_.CancelAllFindSessions();
 
-  // Update the current zoom factor for the new page.
-  ui_zoom::ZoomController* zoom_controller =
-      ui_zoom::ZoomController::FromWebContents(web_contents());
-  DCHECK(zoom_controller);
-  current_zoom_factor_ =
-      content::ZoomLevelToZoomFactor(zoom_controller->GetZoomLevel());
-
   if (web_view_guest_delegate_) {
     web_view_guest_delegate_->OnDidCommitProvisionalLoadForFrame(
         !render_frame_host->GetParent());
@@ -1048,18 +1071,14 @@ void WebViewGuest::SetName(const std::string& name) {
 }
 
 void WebViewGuest::SetZoom(double zoom_factor) {
-  auto zoom_controller =
-      ui_zoom::ZoomController::FromWebContents(web_contents());
+  auto zoom_controller = ZoomController::FromWebContents(web_contents());
   DCHECK(zoom_controller);
   double zoom_level = content::ZoomFactorToZoomLevel(zoom_factor);
   zoom_controller->SetZoomLevel(zoom_level);
+}
 
-  scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
-  args->SetDouble(webview::kOldZoomFactor, current_zoom_factor_);
-  args->SetDouble(webview::kNewZoomFactor, zoom_factor);
-  DispatchEventToView(
-      new GuestViewBase::Event(webview::kEventZoomChange, args.Pass()));
-  current_zoom_factor_ = zoom_factor;
+void WebViewGuest::SetZoomMode(ZoomController::ZoomMode zoom_mode) {
+  ZoomController::FromWebContents(web_contents())->SetZoomMode(zoom_mode);
 }
 
 void WebViewGuest::SetAllowTransparency(bool allow) {
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.h b/extensions/browser/guest_view/web_view/web_view_guest.h
index 6bd2921..d6f3e32 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.h
+++ b/extensions/browser/guest_view/web_view/web_view_guest.h
@@ -62,6 +62,12 @@ class WebViewGuest : public GuestView<WebViewGuest>,
       int embedder_process_id,
       int web_view_instance_id);
 
+  // Get the current zoom.
+  double GetZoom() const;
+
+  // Get the current zoom mode.
+  ui_zoom::ZoomController::ZoomMode GetZoomMode();
+
   // Request navigating the guest to the provided |src| URL.
   void NavigateGuest(const std::string& src, bool force_navigation);
 
@@ -79,6 +85,9 @@ class WebViewGuest : public GuestView<WebViewGuest>,
   // Set the zoom factor.
   void SetZoom(double zoom_factor);
 
+  // Set the zoom mode.
+  void SetZoomMode(ui_zoom::ZoomController::ZoomMode zoom_mode);
+
   void SetAllowScaling(bool allow);
 
   // Sets the transparency of the guest.
@@ -106,6 +115,7 @@ class WebViewGuest : public GuestView<WebViewGuest>,
   void GuestReady() override;
   void GuestSizeChangedDueToAutoSize(const gfx::Size& old_size,
                                      const gfx::Size& new_size) override;
+  void GuestZoomChanged(double old_zoom_level, double new_zoom_level) override;
   bool IsAutoSizeSupported() const override;
   bool IsDragAndDropEnabled() const override;
   void WillAttachToEmbedder() override;
@@ -176,9 +186,6 @@ class WebViewGuest : public GuestView<WebViewGuest>,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
-  // Returns the current zoom factor.
-  double zoom() const { return current_zoom_factor_; }
-
   // Begin or continue a find request.
   void StartFindInternal(
       const base::string16& search_text,
@@ -385,9 +392,6 @@ class WebViewGuest : public GuestView<WebViewGuest>,
   using PendingWindowMap = std::map<WebViewGuest*, NewWindowInfo>;
   PendingWindowMap pending_new_windows_;
 
-  // Stores the current zoom factor.
-  double current_zoom_factor_;
-
   // Determines if this guest accepts pinch-zoom gestures.
   bool allow_scaling_;
   bool is_guest_fullscreen_;
diff --git a/extensions/common/api/web_view_internal.json b/extensions/common/api/web_view_internal.json
index 5440e90..c819408 100644
--- a/extensions/common/api/web_view_internal.json
+++ b/extensions/common/api/web_view_internal.json
@@ -63,6 +63,25 @@
             "description": "Remove data accumulated on or after this date, represented in milliseconds since the epoch (accessible via the <code>getTime</code> method of the JavaScript <code>Date</code> object). If absent, defaults to 0 (which would remove all browsing data)."
           }
         }
+      },
+      {
+        "id": "ZoomMode",
+        "type": "string",
+        "description": "Defines the how zooming is handled in the webview.",
+        "enum": [
+          {
+            "name": "per-origin",
+            "description": "Zoom changes will persist in the zoomed page's origin, i.e. all other webviews in the same partition that are navigated to that same origin will be zoomed as well. Moreover, <code>per-origin</code> zoom changes are saved with the origin, meaning that when navigating to other pages in the same origin, they will all be zoomed to the same zoom factor."
+          },
+          {
+            "name": "per-view",
+            "description": "Zoom changes only take effect in this webview, and zoom changes in other webviews will not affect the zooming of this webview. Also, <code>per-view</code> zoom changes are reset on navigation; navigating a webview will always load pages with their per-origin zoom factors (within the scope of the partition)."
+          },
+          {
+            "name": "disabled",
+            "description": "Disables all zooming in the webview. The content will revert to the default zoom level, and all attempted zoom changes will be ignored."
+          }
+        ]
       }
     ],
     "functions": [
@@ -179,6 +198,54 @@
         ]
       },
       {
+        "name": "setZoomMode",
+        "type": "function",
+        "description": "Sets the zoom mode of the webview.",
+        "parameters": [
+          {
+            "type": "integer",
+            "name": "instanceId",
+            "description": "The instance ID of the guest <webview> process."
+          },
+          {
+            "$ref": "ZoomMode",
+            "name": "ZoomMode",
+            "description": "Defines how zooming is handled in the webview."
+          },
+          {
+            "type": "function",
+            "name": "callback",
+            "description": "Called after the zoom mode has been changed.",
+            "optional": true,
+            "parameters": []
+          }
+        ]
+      },
+      {
+        "name": "getZoomMode",
+        "type": "function",
+        "description": "Gets the current zoom mode.",
+        "parameters": [
+          {
+            "type": "integer",
+            "name": "instanceId",
+            "description": "The instance ID of the guest <webview> process."
+          },
+          {
+            "type": "function",
+            "name": "callback",
+            "description": "Called with the webview's current zoom mode.",
+            "parameters": [
+              {
+                "$ref": "ZoomMode",
+                "name": "ZoomMode",
+                "description": "The webview's current zoom mode."
+              }
+            ]
+          }
+        ]
+      },
+      {
         "name": "find",
         "type": "function",
         "description": "Initiates a find-in-page request.",
diff --git a/extensions/renderer/resources/guest_view/web_view/web_view_api_methods.js b/extensions/renderer/resources/guest_view/web_view/web_view_api_methods.js
index f880a86..e42396e 100644
--- a/extensions/renderer/resources/guest_view/web_view/web_view_api_methods.js
+++ b/extensions/renderer/resources/guest_view/web_view/web_view_api_methods.js
@@ -42,6 +42,9 @@ var WEB_VIEW_API_METHODS = [
   // Gets the current zoom factor.
   'getZoom',
 
+  // Gets the current zoom mode of the webview.
+  'getZoomMode',
+
   // Navigates to a history entry using a history index relative to the current
   // navigation.
   'go',
@@ -70,6 +73,9 @@ var WEB_VIEW_API_METHODS = [
   // Changes the zoom factor of the page.
   'setZoom',
 
+  // Changes the zoom mode of the webview.
+  'setZoomMode',
+
   // Stops loading the current navigation if one is in progress.
   'stop',
 
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index ee790d6..54d370a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -49889,6 +49889,8 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="990" label="SETTINGSPRIVATE_GETPREF"/>
   <int value="991" label="NETWORKINGPRIVATE_FORGETNETWORK"/>
   <int value="992" label="EASYUNLOCKPRIVATE_HIDEERRORBUBBLE"/>
+  <int value="993" label="WEBVIEWINTERNAL_SETZOOMMODE"/>
+  <int value="994" label="WEBVIEWINTERNAL_GETZOOMMODE"/>
 </enum>
 
 <enum name="ExtensionInstallCause" type="int">